at a time

​separately or in groups of two, three, etc. on each occasion

We had to go and see the principal one at a time.

She ran up the stairs two at a time.

He surfs the internet for hours at a time.

When we said "She ran up the stairs two at a time.", it could be

  • There were a group of children for example playing running up the stairs.

  • They divided into many groups of two.

  • Each group ran up the stairs at a time.

  • She & her friend ran up the stairs together.

Do I understand it correctly?

5 Answers 5


As it says "She ..." we are talking about one girl, and not a group of girls.

So it can't mean that there was a group that divided into pairs and each pair ran together.

Instead it means that she took two steps of the stairs in one stride. Normally you tread on each step of the stairs. If you are running you might go over two steps. This is what is meant by "two at a time". It means two steps, not two girls.

If you said

They ran up the steps two at a time.

The sentence is ambiguous. But ambiguous is not always bad. In context it would be understood and it avoids the repetition of "They ran up the steps two steps at a time."

Native speakers generally don't use any more words than they need to. Talking about 'treads' or 'risers' is too formal and unnecessary. These words are used by builders and people who make, repair, or install stairs.

  • 13
    Native speakers generally don't use any more words than they need to. Talking about 'treads' or 'risers' is too formal and unnecessary. These words are used by builders and people who make, repair, or install stairs. Mar 22, 2020 at 9:35
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    To describe a person ascending or descending stairs in a hurry, we can say e.g. 'she took the stairs two at a time'. Mar 22, 2020 at 11:54
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    @Tom why would you? Firstly 'treads' and 'risers' aren't the terms for stairs, but for parts of a stair; you'd have trouble running up risers as they are the vertical parts. Also, just like you wouldn't say 'She ate the sweets two sweets at a time' as it is excessively repetitive, so 'She run up the stairs two stairs at a time' becomes 'She run up the stairs two at a time" as the singular stair is also one step of a staircase. Mar 22, 2020 at 17:45
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    I don't agree that "They ran up the steps two at a time." is ambiguous. To me this still says unambiguously that two (or more) people are running up stairs skipping every other step. Sure it could be interpreted the other way, but most English speakers wouldn't, since the fact there's more than one person is already implied by "they", so it'd be redundant. If you wanted to say they were running in pairs, you'd more likely just explicitly say "They ran up the stairs in pairs." Mar 22, 2020 at 20:03
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    @IlmariKaronen: As a USA native I've certainly used the term "stair" used as a singular, but not nearly as often as "step". If one were to say "A handrail is not needed for landings that are at most three steps above the ground", that would be regarded as much clearer than "...three stairs above the ground".
    – supercat
    Mar 22, 2020 at 22:43

It's a singular "she", so it's not about pairs or groups of children running. "Two at a time" refers to the stairs. She is skipping alternating steps, ascending two steps with each stride.


It simply means that she took two steps at a time. To better visualise it she skipped one step each time she took a stride.


The second sentence strikes me as atypical English usage. A more typical way of writing it would be "She ran up the steps two at a time", meaning that she ascended two steps with each stride. Although "stair" can be used as a singular noun, the word "step" is used far more often for that purpose. If someone goes "up the stairs" from the first to the second floor, it would generally mean that they ascended either a staircase or two staircases connected by a landing, but that the details of the staircase(s) aren't of interest to the writer and shouldn't be of interest to the reader. By contrast, saying "up the steps" would suggest that the steps themselves of interest. Adding the phrase "two at a time" would make clear why.

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    Where are you from? Your expectation is very different from mine (southern England), where ‘steps’ wouldn't normally refer to a staircase — not a domestic one, at least. (You'd be more likely to use it for a few steps up from the pavement to the front door.) Conversely, ‘going up (or down) stairs two at a time’ would be a very common and natural way to refer to someone going between storeys as fast as they could.
    – gidds
    Mar 22, 2020 at 23:18
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    I wouldn't normally say "ran up the steps" unless I was trying to call attention to the individual steps within the staircase.
    – supercat
    Mar 23, 2020 at 0:10
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    I don't think so, at least in American English. You'd say "ran up the stairs" if it was a staircase, but "ran up the steps" if it was a broad set of steps, such as might be found in front of public buildings.
    – jamesqf
    Mar 23, 2020 at 3:41
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    @jamesqf seems interchangable in my view. I don't think most people have such a narrow interpretation of what stair or step means
    – eps
    Mar 23, 2020 at 15:47
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    I'm also midwestern, and while I understand the reason for your distinction, I would never consider it wrong to refer to stairs individually—informal at worst, but perfectly common. Mar 24, 2020 at 5:25

The singular "time" here means one occurrence or event or "occasion" as Oxford mentions. "At a time" means "during each event." There may be some ambiguity in certain cases as others have pointed out, but the main idea can generally be determined from the context. If I take my pills four at a time, that could mean I'm swallowing all four pills in one gulp or it could mean I'm swallowing one pill and then immediately swallowing the next pill after it and so on but the main idea is that I'm not spreading the pills out through the day (meaning I'm not taking two in the morning and two at night for example).

We had to go and see the principal one at a time. In this case one "time" is one session with the principal. No two students were seeing the principal simultaneously. Each talk with the principal involved only one student.

He surfs the internet for hours at a time. Similarly, a "time" here is an Internet session. Rather than using the Internet for just a few minutes before going to do something else, he spends consecutive hours on the Internet between each break.

She ran up the stairs two at a time. Like others have said, each "time" is each stride/step she takes. So during each stride (each occurrence of either foot landing) she will ascend two stair steps instead of one. This isn't ambiguous in terms of how many people are involved because "she" is singular, but the terms we use like "stair" and "step" can be ambiguous. "Stair" can mean a whole flight of stairs but we know it means a single step in this case and I've said "stair step" to be extra clear. "Step" is also ambiguous because it can mean a single stair step in a staircase or it can refer to the action of stepping as in "take a step forward" but I've tried to be clear in my meaning.

  • Kyle, a very informative comment! Nevertheless, could you be so kind to clarify your message by taking out some things not related to the word "time" (maybe, about ambiguities)? Thanks in advance! Mar 23, 2020 at 20:41
  • Thanks for the feedback Andrew. By calling this a comment, do you mean to imply that it was not appropriate to post it as an answer? Also, I'm happy to edit it for clarity but can you explain more about why removing the section about ambiguities would help? The original question was not just about time. It was specifically about the whole phrase "She ran up the stairs two at a time" which involves stairs. Mar 23, 2020 at 21:02
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    Kyle, I have mistyped, that's an appropriate answer! I just wanted to mention that such kind of solution is very detailed though can be quite complex for understanding to Tom, who asked this question. I am not imposing, it is up to you. Thanks for understanding! Mar 24, 2020 at 8:10

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